This information is part of the Modelica Standard Library maintained by the Modelica Association.

Description in VHDL is given by http://www.cs.sfu.ca/~ggbaker/reference/std_logic/src/std_logic_entities.vhd

Truth Table for high active reset:

DataIn	Enable	Reset	DataOut	Map
*	*	U	U	1
*	*	1	0	2
*	0	0	NC	3
*	1	0	DataIn	3
*	X	0	X or U or NC	3
*	U	~1	U	4
*	~U	X	X or U or 0 or NC	4

Truth Table for low active reset:

DataIn	Enable	Reset	DataOut	Map
*	*	U	U	1
*	*	0	0	2
*	0	1	NC	3
*	1	1	DataIn	3
*	X	1	X or U or NC	3
*	U	~0	U	4
*	~U	X	X or U or 0 or NC	4

  *  = do not care
  ~  = not equal
  U  = L.'U'
  0  = L.'0' or L.'L'
  1  = L.'1' or L.'H'
  X  = L.'X' or L.'W' or L.'Z' or L.'-'
  NC = no change

ResetMap	Value: {1, 4, 3, 2, 4, 4, 3, 2, 4} Type: Integer[L] Description: function selection, defaults for high active reset
strength	Value: S.'S_X01' Type: Strength Description: output strength
n	Value: 1 Type: Integer Description: data width